.black-nav{
    width: 100%;
    line-height: 40px;
    height: 40px;
    background: #333;
    font-size: 12px;
    color: #b0b0b0;
}
.w{
    width: 1226px;
    margin: 0 auto;
    position: relative;
}
.black-nav .w ul{
    margin: 0 auto;
}
.black-nav .black-nav-left{
    float: left;
    height: 40px;
    line-height: 40px;
    padding-left: 0px;
}
.black-nav .black-nav-right{
    float: right;
    height: 40px;
    line-height: 40px;
}
.black-nav .w li{
    float: left;
    position: relative;
}
.black-nav .w li span{
    color: #424242;
    margin: 0 5px;
}
.black-nav .w a{
    color: #b0b0b0;
}
.black-nav .w ul a:hover{
    color: #fff;
}
.download{
    width: 124px;
    height: 0px;
    background: #fff;
    box-shadow: 0 1px 5px #aaa;
    position: absolute;
    top: 40px;
    left: 50%;
    overflow: hidden;
    margin-left: -65px;
    z-index: 3;
}
.download img{
    width: 90px;
    height: 90px;
    margin: 18px auto 12px;
}
.download p{
    color: #000;
    font-size: 14px;
    line-height: 0px;
    position: absolute;
    top: 75%;
    left: 20px;
}
.black-nav-left li:hover>.download{
    height: 150px;
    transition: all 0.5s;
}
.cart{
    width: 120px;
    height: 40px;
    background-color: #424242;
    margin-left: 25px;
}
.cart em{
    font-style: normal;
}
.cart:hover{
    background: #fff;
    color: #ff6700;
}
.gouwu{
    width: 316px;
    height: 0px;
    background: #fff;
    box-shadow: 0 1px 5px #aaa;
    position: absolute;
    right: 0;
    top: 40px;
    color: #424242;
    overflow: hidden;
    line-height: 100px;
    z-index: 3;
}
.cart:hover>.gouwu{
    height: 100px;
    transition: all 0.5s;
}